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Remember science class when the teacher shouted “Pay attention! You might need this someday!” ? Well, as much as I don’t want to admit it, that teacher was right. Lets touch upon the basics and see if it rings a bell?

The Basics:

First off – MAP is an acronym for Manifold Absolute Pressure. MAP sensors measure the air pressure in your intake manifold which helps the engine’s computer determine air / fuel ratios. MAP sensors are set to “zero” from the factory. So with the car off, and the key on, the MAP sensor will read “zero” at sea level.

On earth, we have 14.7 Pounds per Square Inch (PSI) on us at all times at sea level.

“Bar” is a measurement of pressure. 1 Bar = 1 atmospheric pressure, which is 14.7 PSI.

The absence of pressure is measured in “Inches Of Mercury” (in. hg). (Finally we get to use the periodic table of elements in real life!)

-1 Bar = -29.4 in. hg

1 Bar = 29.4 in. hg

Naturally Aspirated = without a turbocharger or supercharger. Also known as “N/A”.

Forced Induction = with a turbo or supercharger

In forced induction applications “Boost” is automotive slang for PSI

Stoichiometric Air Fuel Ratio = The ratio of the exact amount of air it takes to burn a fuel completely.